Organic Food: Buying More Safety or Just Peace of Mind? A Critical Review of the Literature

Figures & data

Table 1 Major categories of synthetic pesticides

• Organophosphates

• Carbamates

• Pyrethroids

• Insect juvenile hormones and analogues

• Compounds that affect other metabolic pathways

• Compounds that affect insect behavior

• Aryloxyalkanoic acids

• 2-(4-aryloxyphenoxy)propionic acids

• Triazines

• Fungicides

• Metabolites

Derived from Plimmer (2001).

Table 2 The elements of hazard characterization of dietary chemicals

• Establishment of the dose-response relationship for critical effects.

• Assessment of external vs. internal dose.

• Identification of the most sensitive species and strain.

• Identification of potential species differences (qualitatively and quantitatively).

• Characterization of the mode of action/the mechanism for the critical effects.

• Extrapolation from high to low dose and from experimental animals to humans.

Derived from Dybing et al. (2002).

Figure 1. Frequency of detecting at least one type of pesticide residue in organic and conventional fruits and vegetables. Data on pesticide residues in organically grown foods (gray bars) and foods with no market claim (assumed to be conventionally grown; black bars) were collected from the Pesticide Data Program of the US Department of Agriculture. The total number of samples tested is shown on top of the respective bars. Derived from Baker et al. (2002).

Figure 2. Ten-year trends of contamination rates with pesticides of organic and conventional fruits and vegetables. Data on pesticide residues in organically grown foods (gray squares) and foods with no market claim (assumed to be conventionally grown; black squares) were collected from the Marketplace Surveillance Program of the California Department of Pesticide Regulation. A total of 67,154 samples (1,097 organic and 66,057 conventional) were examined. Derived from Baker et al. (2002).

Figure 3. Organochlorine and non-organochlorine pesticide residues in organic and conventional vegetables. Data on organochlorine pesticide (OCP) and non-OCP residues in organically grown vegetables (97 samples, gray bars) and those with no market claim (assumed to be conventionally grown; 13,959 samples, black bars) were collected from the Pesticide Data Program of the US Department of Agriculture. Residue detection frequencies are shown on top of the respective bars, and have been determined for all the pesticides combined, for pesticides other than the OCPs, and for the OCPs only. The latter category, therefore, represents food samples containing only OCP residues. Derived from Baker et al. (2002).

Figure 4. Pesticide residues in organic and conventional olive oil. Residues of fenthion (squares) and dimethoate (triangles) pesticides were determined in organic and conventional olive oils from Crete during 1997–1999. The ratio of the mean concentration of conventional to that of organic produce is shown. Derived from Tsatsakis et al. (2003).

Figure 5. Factors affecting cadmium input to soil and uptake by plants. Derived from Linden et al. (2001) and Moolenaar and Lexmond (1999).

Figure 6. Nitrate content of organic and conventional crops. The results from 18 published studies including a total of 176 comparisons on the nitrate content of organic and conventional crops, including beetroot, cabbage, carrot, celeriac, chard, corn salad, endive, kale, leek, lettuce, potato, radish, spinach, and turnip, are presented. The percent of total comparisons indicating lower (gray bars), equal (white bars), or higher (black bars) nitrate content in organic compared with conventional produce is shown. Derived from Worthington (2001).

Table 3 Pesticides approved for use in organic farming

Active ingredients	Use	Properties
Copper ammonium carbonate	Banned after 2002*	Copper salts are effective against some fungal disease
Copper sulfate	≫
Copper oxychloride	≫
Sulfur	Permitted	Used for control of some fungal disease
Soft soap	Permitted	Used for aphid control
Rotenone	Under review	Naturally occurring plant-based insecticide
		Asserted to decompose rapidly in the environment
Biological control agents (e.g. predatory lacewings)	Permitted	Used for control of microbial disease outbreaks
Bacillus thuringiensis (Bt) spores	Restricted	Used for pest control
Other insecticides (e.g. natural pyrethrins)	Permitted	Asserted to have no systemic activity
Derived from Fookes and Dalmeny (2001).

Table 4 The health risks of some organic pesticides

Substance	Adverse effects	Reference
Rotenone	• Causes death in fish.	MacKenzie, 1993
	• Induces Parkinson's disease.	Betarbet et al., 2000
	• Inhibits the mitochondrial electron transport chain.	Bashan et al., 1993
	• Induces hepatocyte apoptosis.	Isenberg and Klaunig, 2000
Bacillus thuringiensis (Bt)	• Remains persistent in soil and plant leafs.	Smith and Barry, 1998
	• Produces Bacillus cereus-like cytolytic toxins.	Tayabali and Seligy, 2000
	• Causes cutaneous inflammatory lesions in immunosuppressed mice after subcutaneous injection. ^a	Hernandez et al., 1998
	• Causes lung inflammation, internal bleeding and death in immunocompetent mice after administration by the pulmonary route. ^a	Hernandez et al., 1999
	• Infects wounds from traumatized (and probably immunosuppressed) human patients.	Hernandez et al., 1998; Damgaard et al., 1997
	• Has been implicated in a gastroenteritis outbreak, along with Bacillus cereus and Norwalk virus.	Jackson et al., 1995
Natural pyrethrins ^b	• Although some are equally toxic against houseflies (the expected effect), the toxicity to mammals can be more than 40-fold higher for certain pyrethrins than for the respective pyrethroids.	Aitio, 2002
	• Most pyrethrins are less effective than the respective pyrethroids and have to be used at higher doses.	Trewavas, 2001
	• Several pyrethrins and pyrethroids are equally neurotoxic in rodents.	Dorman, 1991
	• Residues of both types have been detected in food, but in acceptable amounts.	Nakamura et al., 1993

Figure 7. Use of potentially hazardous practices among organic producers. During December 1997 and January 1998, a fifteen-page questionnaire was mailed to 4,638 certified organic producers throughout the US, asking for information about a variety of topics corresponding to their farms. For the practices shown in the figure, respondents (approximately 1,060 for each category) were asked to indicate their frequency of use pertaining to each of the management strategies or materials shown. Derived from Walz (1999).

Figure 8. Microbiological status of organic and conventional chard. The native microflora of fresh Swiss chard (Beta vulgaris, type cicla) cultivated by organic (Ponce et al., 2003) (gray bars) and conventional (Ponce et al., 2002) (black bars) methods was quantified and characterized from 28 different samples of each type. Values are shown as mean ± standard deviation. No significant differences in the microbial populations between the two types of produce were identified. Derived from Ponce et al. (2002, 2003).

Table 5 Mycotoxin contamination in organic and conventional cereal crops

Food sampled	Mycotoxins	Main findings	Reference
Wheat (n = 22) and barley (n = 10).	DON 3-ADON	• Incidence of DON contamination was lower in Org. vs. Conv. wheat (54.5 vs. 90.9%, respectively) and barley (60 vs. 80%, respectively).	Malmauret et al., 2002
	15-ADON NIV	• Median levels of DON were higher in Org. vs. Conv. wheat (106 vs. 55 μ g/kg, respectively) and barley (69 vs. 41 μ g/kg, respectively).
	T-2 HT-2	• Incidence of 3-ADON contamination was higher in Org. vs. Conv. wheat (9.1 vs. 0%, respectively); it was not detected in either barley type.
	ZEA DAS FB1 OTA	• Incidence of NIV contamination was higher in Org. vs. Conv. wheat (90.9 vs. 0%, respectively) and barley (80 vs. 20%, respectively).
		• Median levels of NIV were higher in Org. vs. Conv. barley (83 vs. 10 μ g/kg, respectively); median levels of NIV in Org. wheat were low (10 μ g/kg).
		• Incidence of HT-2 contamination was higher in Org. vs. Conv. wheat (9.1 vs. 0%, respectively) and barley (40 vs. 0%, respectively).
		• Median levels of HT-2 in both Org. wheat and barley were 50 μ g/kg.
		• Incidence of ZEA contamination was lower in Org. vs. Conv. barley (0 vs. 40%, respectively); it was not detected in either wheat type.
		• Median levels of ZEA in Conv. barley were low (1.25 μ g/kg).
		• None of the remaining mycotoxins were detected.
Winter wheat during 1997 and 1998.	DON	• Mean levels of DON contamination for 1997 were lower in Org. vs. Conv. crops (approximately 100 vs. 150 μ g/kg, respectively), but the reverse was true for 1998 (approximately 300 vs. 150 μ g/kg, respectively).	Birzele et al., 2002
Rye (n = 100) and wheat (n = 101).	DON ZEA	• Incidence of DON contamination was higher in Org. vs. Conv. rye (56 vs. 40%, respectively), but the reverse was true for wheat (76 vs. 88%, respectively).	Mark et al., 1995
		• Mean levels of DON were higher in Org. vs. Conv. rye (427 vs. 160 μ g/kg, respectively), but did not differ in wheat (486 vs. 420 μ g/kg, respectively).
		• Mean levels of ZEA were higher in Org. vs. Conv. rye (51 vs. 4 μ g/kg, respectively) and wheat (24 vs. 6 μ g/kg, respectively).
Cereal-based foods (n = 237), including bread and bread-related products (n = 96), noodles (n = 29), breakfast cereal (n = 32), baby food (n = 25), rice (n = 26), and other cereal-based products (n = 29).	DON 3-ADON 15-ADON NIV FUS-X T-2 HT-2 ZEA α-ZOL β-ZOL	• Incidence of DON contamination was lower in Org. vs. Conv. food (55 vs. 77%, respectively).	Schollenberger et al., 1999
		• Median levels of DON were lower in Org. vs. Conv. food (28 vs. 62 μ g/kg, respectively).
		• Mean levels of DON were similar between Org. and Conv. food (128 ± 304 and 97 ± 103 μg/kg, respectively).
		• Maximum levels of DON were higher in Org. vs. Conv. food (1,670 vs. 624 μ g/kg, respectively).
		• FUS-X, ZEA, α- and β-ZOL were not detected.
		• Results for other toxins are not reported. No difference?
Cereal-based baby food (n = 164), including semolina (n = 40), rice (n = 48), multi-cereal (n = 42), and maize and tapioca (n = 34) formulas.	OTA	• Overall incidence of OTA contamination was lower in Org. vs. Conv. food (15 vs. 33.3%, respectively). However, it varied among individual foods: it was lower in Org. vs. Conv. semolina (10 vs. 60%, respectively) and multi-cereal (0% vs. 80%, respectively) formulas, but higher in rice formulas (45.5 vs. 0%, respectively), and not different in maize/tapioca formulas, where no OTA was detected.
		• Levels of OTA were generally not different: 0.18 and 0.14–0.65 μ g/kg for Org. and Conv. semolina formulas, 0.1–0.4 μ g/kg for Conv. multi-cereal formulas, and 0.24–0.74 μ g/kg for Org. rice formulas.
Cereal crops (n = 237), including rye (n = 100), wheat (n = 71), and barley (n = 66).	OTA	• Overall incidence of OTA contamination was higher in Org. vs. Conv. produce (19.9 vs. 3.6%, respectively). This finding was consistent among all three individual crops, i.e. rye (37.5 vs. 5.8%, respectively), wheat (19.9 vs. 0%, respectively), and barley (7.9 vs. 3.9%, respectively).	Czerwiecki et al., 2002a
		• Overall mean levels of OTA were higher in Org. vs. Conv. produce (5.7 vs. 1.11 μ g/kg, respectively). This finding was consistent among both rye (3.17 vs. 1.38 μ g/kg, respectively) and especially barley (25.73 vs. 0.3 μ g/kg, respectively); mean OTA levels in Org. wheat were low (0.83 μ g/kg).
Cereal crops (n = 207), including rye (n = 83), wheat (n = 71), and barley (n = 53).	OTA	• Overall incidence of OTA contamination was similar between Org. and Conv. produce (15.5 vs. 20.9%, respectively), but varied among the individual crops. It was similar in Org. vs. Conv. rye (10.9 vs. 10.8%, respectively), lower in wheat (23.5 vs. 48.6%, respectively), and higher in barley (11.8 vs. 5.5%, respectively).	Czerwiecki et al., 2002b
		• Overall mean levels of OTA were 25.5-fold lower in Org. vs. Conv. produce (7.92 vs. 202 μ g/kg, respectively). This finding was due to the large difference in Org. vs. Conv. wheat (1.17 vs. 267 μ g/kg, respectively), while OTA levels in rye and barley were higher in Org. crops (14.5 and 18.4 μ g/kg, respectively) compared with Conv. ones (6.75 and 5.45 μ g/kg, respectively).
Wheat (n = 196) and rye (n = 69).	DON ZEA	• Incidence of DON contamination was lower in Org. vs. Conv. wheat (54 vs. 69%, respectively), and rye (11 vs. 34%, respectively).	Doll et al., 2002
		• Mean levels of DON were lower in Org. vs. Conv. wheat [760, 1, 540], and rye (130 vs. 490 μ g/kg dm, respectively).
		• Median levels of DON were similar between Org. and Conv. wheat (230 vs. 270 μ g/kg dm, respectively); median levels in both types of rye were below detection limit.
		• Maximum levels of DON were lower in Org. vs. Conv. wheat (4,220 vs. 11,660 μ g/kg dm, respectively), and rye (130 vs. 3,090 μ g/kg dm, respectively).
		• Incidence of ZEA contamination was low and similar between Org. and Conv. wheat (4 vs. 7%, respectively); rye was not analyzed.
		• Mean levels of ZEA were lower in Org. vs. Conv. wheat (47 vs. 74 μ g/kg dm, respectively).
		• Median levels of ZEA for both types of wheat were below detection limit.
		• Maximum levels of ZEA were lower in Org. vs. Conv. wheat (55 vs. 250 μ g/kg dm, respectively).
Wheat kernels (n = 419) and flour (n = 276) and rye kernels (n = 422) and flour (n = 320) during 1992–1999.	OTA	• Multiyear incidence of OTA was generally low and similar between Org. and Conv. wheat grains (0 vs. 1.2%, respectively) and flour (0.8 vs. 0.6%, respectively).	Jorgensen et al., 2002
		• Multiyear mean concentration of OTA was similar between Org. and Conv. wheat grains (0.3 vs. 0.3 μ g/kg, respectively) and flour (0.5 vs. 0.3 μ g/kg, respectively).
		• Multiyear incidence of OTA was higher in Org. vs. Conv. rye grains (11.8 vs. 3.2%, respectively), but it was similar in flour (5.2 vs. 3.6%, respectively).
		• Multiyear mean concentration of OTA was higher in Org. vs. Conv. rye grains (3.9 vs. 0.9 μ g/kg, respectively) and flour (1.8 vs. 0.8 μ g/kg, respectively).
Wheat flour (n = 60).	DON 3-ADON 15-ADON NIV FUS-X T-2 HT-2 ZEA α-ZOL	• Incidence of DON contamination was high but similar between Org. and Conv. samples (96 vs. 100%, respectively).	Schollenberger et al., 2002
		• Median levels of DON were lower in Org. vs. Conv. samples (120 vs. 295 μ g/kg, respectively).
		• Mean levels of DON were not significantly different between Org. and Conv. samples (131 ± 150 and 394 ± 341 μ g/kg, respectively).
		• Maximum levels of DON were lower in Org. vs. Conv. samples (756 vs. 1,379 μ g/kg, respectively).
		• FUS-X, α- and β-ZOL were not detected.
	β-ZOL	• Results for other toxins are not reported. No difference?
Winter wheat (n = 130) during 1997–2001.	DON	• Overall incidence of DON contamination was low and not different between Org. and Conv. crops (8.3 and 13.2%, respectively).	Lucke et al., 2003
		• Maximum DON levels recorded each year throughout the observation period were also similar between Org. and Conv. crops (60–698 vs. 104–880 μ g/kg, respectively).
Cereal-based foods (n = 346). Cereals included wheat, hard wheat, rice, spelt, barley, oats, and rye. The food products included flours, bakery products (mainly crackers), and baby foods.	OTA	• With respect to commercial flours and their derivatives, there were no significant differences between Org. and Conv. samples.	Biffi et al., 2004
		• Some baby foods (semolina) from conventional production had higher content of OTA than the corresponding Org. products, while the reverse was true for rice formulas.
Various types of bread from rye, wheat, or mixed cereals (n = 101).	DON	• Incidence of DON was higher in Conv. than in Org. samples (96 vs. 82%, respectively).	Schollenberger et al., 2005
		• There was a strong trend (P = 0.059) for DON concentration (in μ g/kg) to be higher in Conv. samples (median = 161; mean = 184; range = 15–690) than in Org. (median = 46; mean = 62; range = 15–224).
		• These results were similar for all types of bread examined.
Org. is organic and Conv. is conventional; n represents the total number of organic and conventional samples analyzed.
Mycotoxins: DON is deoxynivalenol, ZEA is zearalenone, 3-ADON is 3-acetyl-deoxynivalenol, 15-ADON is 15-acetyl-deoxynivalenol, NIV is nivalenol, FUS-X is fusarenon-X, T-2 is T-2 toxin, HT-2 is HT-2 toxin, α-ZOL is α-zearalenol, β-ZOL is β-zearalenol, OTA is ochratoxin A, DAS is diacetoxyscirpenol, and FB1 is fumonisin B1.
Mean levels of the various mycotoxins have been derived from the positive samples only, while median refers to all samples, and maximum refers to the sample with the highest concentration.

Figure 9. Patulin contamination in organic and conventional fresh apples and apple juice. Twelve samples of fresh apples (2 kg/sample) (Malmauret et al., 2002) and twenty-one commercially available apple juices (Beretta et al., 2000) from organic and conventional production were analyzed for the presence of patulin. Values are shown as mean ± standard deviation. *P < 0.05 vs. conventional produce. Derived from Malmauret et al. (2002) and Beretta et al. (2000).

Figure 10. Deoxynivalenol contamination in organic and conventional wheat. Eleven conventional and eleven organic samples of wheat (1 kg/sample) were tested for the presence of deoxynivalenol. Median (black squares), mean (black circles), and maximum (black triangles) levels of contamination are shown, along with the frequency of detection of positive samples (gray bars). Derived from Malmauret et al. (2002). Mean levels are reported in Leblanc et al. (2002).

Table 6 Comparison of organic and conventional products with respect to food hazards

Organic < Conventional	Organic = Conventional	Unknown
Synthetic agrochemicals ^a	Environmental pollutants ^d	Natural plant toxins
Nitrate ^b		Biological pesticides
Contaminants in feedstuffs ^c		Pathogenic microbes
Veterinary drugs ^c		Mycotoxins

Figure 11. A simple and interpretative model for consumers' attitude toward food-associated risks. Redrawn with permission after Morasso et al. (2000).

Table 7 Causative agents of foodborne diseases

Biological or chemical agents	Unconventional agents
Bacteria	Prions
• Enterohemorrhagic Escherichia coli (EHEC) (E. coliO157)	Mycotoxins • Fumonisins
• Enteroaggregative E. coli (EAEC)	• Zearalenone
• Listeria monocytogenes	• Trichothecenes
• Multidrug-resistant Salmonella typhimurium DT 104	• Ochratoxins Pesticide residues Environmental contaminants Veterinary drugs Biotechnology Other agents
• Salmonella enteritidis
• Campylobacter jejuni
• Vibrio vulnificus
• Streptococcus parasanguinis
Viruses
• Hepatitis E (HEV)
• Norwalk virus and Norwalk-like viruses Protozoa
• Cyclospora cayetanensis
• Toxoplasma gondii
• Cryptosporidium parvum
Helminths
• The genus Anisakis
Derived from van de Venter (2000).

Figure 12. Relative importance of food hazards for human health. The figure ranks several food hazards according to their potency to cause an acute or chronic effect, regardless of cultivation origin (i.e. organic or conventional). Adapted with permission from Magkos et al. (2003b).

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